The vagina is the opening used for penis-in-vagina intercourse and is the middle of three openings in the vulva area. From front to back, those three openings are the urethra (where urine comes out), the vaginal opening, and the anus. Understanding which opening is which, and what each one is designed for, helps you have safer and more comfortable sex.
The Three Openings and Where They Are
If you’re looking at the vulva (the external genital area), the urethral opening sits at the top, closest to the front of the body. It’s small and can be hard to spot. Below that is the vaginal opening, which is noticeably larger. At the bottom, farthest back, is the anus.
These three openings lead to completely different parts of the body. The urethra is a narrow tube meant only for urine to pass through. The vagina is a stretchy, muscular canal that connects to the cervix and uterus. The anus leads to the rectum and large intestine. Only two of these, the vagina and the anus, are involved in penetrative sex.
The Vagina: The Primary Opening for Intercourse
The vaginal opening is the one most people mean when they talk about “having sex.” It’s a flexible canal, typically about 3 to 4 inches deep when unaroused. During arousal, blood flow increases to the surrounding tissue, and the vagina stretches to roughly 4 to 8 inches in depth. The width changes significantly too. This expansion happens naturally as the body prepares for penetration.
The vagina also produces its own lubrication when aroused, which reduces friction and makes penetration more comfortable. That said, natural lubrication varies from person to person and can be affected by hormones, medications, stress, and hydration. Using additional lubricant is common and perfectly normal, even when arousal is high.
Vaginal intercourse is the type of sex that can result in pregnancy. Condoms, when used correctly every time, protect against unplanned pregnancy 98% of the time and significantly reduce the risk of most sexually transmitted infections.
The Anus: A Secondary Option With Extra Precautions
Some people also have anal sex, which involves penetration of the anus. This is a personal choice, and it requires more preparation than vaginal intercourse for a few important reasons.
First, the anus does not produce its own lubrication. The tissue lining the rectum is thinner than vaginal tissue and tears more easily, which can cause pain, bleeding, and a higher risk of infection. Store-bought lubricant is essential for any kind of anal penetration. Silicone-based lubricant is often preferred because it’s thicker and lasts longer, but water-based lubricant works too. Both types are safe with latex condoms.
Second, bacteria naturally present in and around the anus can cause infections if transferred to the vagina or urethra. If you switch from anal to vaginal contact, always use a fresh condom or wash thoroughly first. The same applies to hands and toys.
Comfort during anal sex depends heavily on relaxation. The muscles around the anus (the sphincters) are tight by default. Taking time to become fully aroused, starting slowly, and communicating with your partner about pace all help prevent pain and injury.
Why the Urethra Is Not for Sex
The urethra is not designed for any kind of sexual penetration. In people with vulvas, it’s an extremely narrow tube with thin walls made of delicate tissue. Attempting to insert anything into it can cause bruising, bleeding, infection, urinary leaking, and lasting damage including scarring that narrows the passage permanently. It is a completely separate opening from the vagina, though the two are close together, which sometimes causes confusion.
Oral Sex Involves Different Anatomy
Oral sex uses the mouth to stimulate a partner’s genitals or anus. It doesn’t involve penetration of a specific “hole” in the same way, but it’s still sex and still carries health considerations. Giving oral sex to a partner with an STI can lead to infections of the mouth and throat, including HPV, gonorrhea, syphilis, and herpes. Receiving oral sex from someone with a mouth or throat infection can transmit infections to the genitals.
Oral contact with the anus specifically can transmit hepatitis A and B, as well as intestinal parasites and bacteria. Dental dams (thin sheets of latex placed over the area) reduce these risks. The risk of HIV transmission through oral sex is much lower than through vaginal or anal sex, but it’s not zero.
Choosing the Right Lubricant
Lubricant makes any type of penetrative sex more comfortable and safer by reducing friction and the chance of tissue tearing. Here’s how the three main types compare:
- Water-based: Safe with all condoms and sex toys. Good for most situations but may need reapplication since it dries out faster. A solid default choice.
- Silicone-based: Lasts longer, works well for anal sex and longer sessions, safe with latex condoms. Not compatible with silicone toys, as it can degrade the material.
- Oil-based: Not safe with latex condoms because oil weakens latex and increases the chance of breakage. Best limited to external use or situations where condoms aren’t involved.
Talking About What You Want
Different people are comfortable with different types of sex, and none of them are obligatory. Talking openly about what you want and don’t want before and during sex makes the experience better for everyone. You can set boundaries around specific body parts, specific activities, or how far you want things to go on a given occasion. Those boundaries can also change at any time, even mid-encounter.
If a partner suggests a type of sex you haven’t discussed or aren’t sure about, that’s a natural moment to speak up. Saying what you do want can be just as useful as saying what you don’t, and it gives both of you clearer information to work with.